Hi,

You can use the "Sum" function in your total field but it will need to use
the same basic expression as the original Expressions Boxes. For example,
let's say you have an Expression Box for each line item that uses the
following expression:

my:field1 + my:field2

If you wanted to have a final Expression Box that totaled all of these Line
Item expressions, it would look like the following:

sum(field1) + sum(field2)

** NOTE: This is using the built-in "builder" - the actual XPath expression
for this is as follows:

sum(my:group1/my:group2/my:field1) + sum(my:group1/my:group2/my:field2)

I hope this helps!

Best Regards,

Scott L. Heim
Microsoft Developer Support

This posting is provided "AS IS" with no warranties, and confers no rights

You'll make life SO much easier on yourself if you store the item's
total amount in a field rather than strictly as an expression box
value. If you don't want to have  item totals as part of your schema,
create a secondary schema and store them there as a set of related
throwaway values.